(1) Field of the Invention
The present invention relates to a process for producing an ion implanted bubble device.
(2) Description of the Prior Art
An ion implanted bubble device comprises bubble propagation tracks which are formed by implanting ions of hydrogen, neon, or helium in a magnetic layer formed on a gadolinium gallium garnet (GGG) substrate by a liquid phase epitaxy process.
One of the important factors which determines the operating margins of the bubble propagation characteristic of an ion implanted bubble device is the implantation induced anisotropy field change .DELTA.Hk. The anisotropy field change .DELTA.Hk must be enhanced to obtain a high grade bubble propagation characteristic. The anisotropy field change .DELTA.Hk depends upon the type of ion and the crystal lattice strain which is induced by the ion implantation.
It is known that increasing the dose of hydrogen ions increases the .DELTA.Hk and makes it possible to obtain a very large .DELTA.Hk compared to that obtainable with helium ions or neon ions using conventional processes. Therefore, in the conventional process of producing an ion implantation bubble device, hydrogen ions are implanted to induce a large .DELTA.Hk and thus obtain a desirable stable bubble propagation characteristic.
Implantation of hydrogen ions, however, takes a very long time. On the other hand, when shortening the ion implantation time, by implanting ions other than hydrogen ions, such as neon or helium ions, a sufficiently large .DELTA.Hk is not induced.